Institute of Primary Care, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
Campus Stiftung Lindenhof Bern (SLB), Bern, Switzerland.
JAMA Netw Open. 2024 Aug 1;7(8):e2425692. doi: 10.1001/jamanetworkopen.2024.25692.
Ferritin is often measured by general practitioners, but the association of different cutoffs with the rates of iron deficiency diagnoses, particularly nonanemic iron deficiency, is unknown.
To investigate the association of the ferritin cutoff choice with the incidence of nonanemic and anemic iron deficiency diagnoses in primary care.
DESIGN, SETTING, AND PARTICIPANTS: In this retrospective cohort study, patients 18 years or older with at least 1 consultation with a general practitioner participating in the Family Medicine Research Using Electronic Medical Records (FIRE) project, an electronic medical records database of Swiss primary care, from January 1, 2021, to November 30, 2023, were evaluated.
Sex, age, clinical patient characteristics, and professional general practitioner characteristics.
Incidence of iron deficiency diagnoses (nonanemic and anemic) at ferritin cutoffs of 15, 30, and 45 ng/mL and ferritin testing itself. Time-dependent Cox proportional hazards regression was used to examine associations of patient and general practitioner characteristics with ferritin testing as adjusted hazard ratios (AHRs).
The study included 255 351 patients (median [IQR] age, 52 [36-66] years; 52.1% female). Per 1000 patient-years and at ferritin cutoffs of 15, 30, and 45 ng/mL, iron deficiency diagnoses had incidences of 10.9 (95% CI, 10.6-11.2), 29.9 (95% CI, 29.4-30.4), and 48.3 (95% CI, 47.7-48.9) cases, respectively; nonanemic iron deficiency diagnoses had incidences of 4.1 (95% CI, 3.9-4.2), 14.6 (95% CI, 14.3-15.0), and 25.8 (95% CI, 25.3-26.2) cases, respectively; and anemic iron deficiency diagnoses had incidences of 3.5 (95% CI, 3.3-3.7), 6.0 (95% CI, 5.8-6.2), and 7.5 (95% CI, 7.3-7.7) cases, respectively. Ferritin testing showed notable associations with fatigue (AHR, 2.03; 95% CI, 1.95-2.12), anemia (AHR, 1.75; 95% CI, 1.70-1.79), and iron therapy (AHR, 1.50; 95% CI, 1.46-1.54). Ferritin testing was associated with female sex in all age groups, including postmenopausal. Of the patients who received ferritin testing, 72.1% received concomitant hemoglobin testing, and 49.6% received concomitant C-reactive protein testing.
In this retrospective cohort study of primary care patients, ferritin cutoffs of 30 and 45 ng/mL were associated with a substantially higher incidence of iron deficiency compared with 15 ng/mL. These results provide a basis for health system-level evaluation and benchmarking of ferritin testing in high-resource settings and call for a harmonization of diagnostic criteria for iron deficiency in primary care.
铁蛋白通常由全科医生测量，但不同截断值与缺铁诊断率（尤其是非贫血性缺铁）的关系尚不清楚。
研究铁蛋白截断值选择与初级保健中铁缺乏诊断（非贫血性和贫血性）发生率的关系。
设计、地点和参与者：这是一项回顾性队列研究，纳入了参与家庭医学研究使用电子病历（FIRE）项目的瑞士初级保健电子病历数据库的至少有一次与全科医生就诊的 18 岁及以上的患者，该研究从 2021 年 1 月 1 日至 2023 年 11 月 30 日进行评估。
性别、年龄、临床患者特征和专业全科医生特征。
铁蛋白截断值为 15、30 和 45ng/ml 时的缺铁诊断（非贫血性和贫血性）发生率和铁蛋白检测本身。采用时间依赖性 Cox 比例风险回归分析评估患者和全科医生特征与铁蛋白检测的关联，作为调整后的风险比（AHR）。
本研究纳入了 255351 名患者（中位数[IQR]年龄为 52[36-66]岁；52.1%为女性）。每 1000 名患者年中，铁蛋白截断值为 15、30 和 45ng/ml 时，缺铁诊断的发生率分别为 10.9（95%CI，10.6-11.2）、29.9（95%CI，29.4-30.4）和 48.3（95%CI，47.7-48.9）；非贫血性缺铁诊断的发生率分别为 4.1（95%CI，3.9-4.2）、14.6（95%CI，14.3-15.0）和 25.8（95%CI，25.3-26.2）；贫血性缺铁诊断的发生率分别为 3.5（95%CI，3.3-3.7）、6.0（95%CI，5.8-6.2）和 7.5（95%CI，7.3-7.7）。铁蛋白检测与疲劳（AHR，2.03；95%CI，1.95-2.12）、贫血（AHR，1.75；95%CI，1.70-1.79）和铁治疗（AHR，1.50；95%CI，1.46-1.54）均有显著关联。在所有年龄组（包括绝经后）中，女性接受铁蛋白检测的比例均高于男性。在接受铁蛋白检测的患者中，72.1%同时接受了血红蛋白检测，49.6%同时接受了 C 反应蛋白检测。
在这项初级保健患者的回顾性队列研究中，与 15ng/ml 相比，铁蛋白截断值为 30 和 45ng/ml 与缺铁的发生率显著升高相关。这些结果为高资源环境中铁蛋白检测的系统水平评估和基准测试提供了依据，并呼吁在初级保健中统一缺铁的诊断标准。
